SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0228 AM CDT Fri Oct 09 2020 Valid 111200Z - 121200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS/UPPER MIDWEST... ...SUMMARY... Isolated strong to severe thunderstorms may occur Sunday across parts of the northern Plains into the Upper Midwest, with marginally severe thunderstorms also possible across parts of the Southeast. ...Northern Plains/Upper Midwest... A large-scale upper trough over western Canada and the northern Rockies should further amplify on Sunday across parts of the northern Plains while gradually acquiring a negative tilt by Sunday night. At the surface, a strong cold front is forecast to sweep east-southeastward from the northern/central Plains into the Upper Midwest through the period in tandem with the amplifying upper trough. Limited low-level moisture return is expected ahead of this advancing cold front, and a low-level inversion may inhibit convective development along the front through much of the day. Still, some potential for storms remains evident from parts of far eastern ND/SD into MN and perhaps parts of IA late Sunday afternoon and continuing into the evening. Strong deep-layer shear will be present across this region, which may act to organize any storms that can develop and subsequently grow upscale along the cold front. Isolated severe wind gusts will probably be the main threat through Sunday evening given a mainly linear mode expected, although some large hail may also occur early in the convective life cycle given the presence of steep mid-level lapse rates. Storms should weaken with eastward extent across the Upper Midwest late Sunday as they outrun the modest forecast instability. ...Southeast... The remnants of Delta are forecast to move northeastward across parts of the TN Valley on Sunday. Modestly enhanced mid-level south-southwesterly winds will remain across parts of the Southeast as a surface warm front lifts slowly northward across parts of the Carolinas. There appears to be enough veering/strengthening of winds with height to support modestly organized storms across the warm sector, with weak to locally moderate instability also forecast. Isolated strong/gusty winds appear to be the main threat, although a brief tornado cannot be ruled out. ..Gleason.. 10/09/2020
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